Claude Mythos 5.1 logo

Claude Mythos 5.1

Anthropic · Lançado 09/2026

Condicional

Same weights as Claude Fable 5.1 at the same $10/$50 rate, with cyber and life-sciences safeguards loosened for vetted users. The catch is access: Mythos 5.1 ships only through Anthropic's trusted-access programs (Cyber Verification and Life Sciences Verification), so there is no self-serve API and no way to buy your way in. Conditional for the same reason as Mythos 5: elite capability behind a vetting gate. Everyone else should use Fable 5.1.

É adequada para ti?

Bom para

  • Vulnerability discovery and offensive-security research — cyber safeguards are loosened relative to Fable 5.1
  • Agentic terminal work at the frontier: 60.9% Terminal-Bench 4.0, 5.1 points above Fable 5.1
  • Life-sciences work that trips Fable 5.1's biology classifiers, for organizations inside the Life Sciences Verification Program

Não recomendado para

  • Any team not admitted to a verification program — there is no public API and no self-serve path
  • General coding and knowledge work — identical price, identical weights, and Fable 5.1 is the one you can actually call
  • Organizations outside the US — Anthropic says access is currently limited to a set of US organizations, with international expansion coordinated with the US government but undated

Desempenho por tarefa

Cybersecurity research

Excellent

Loosened cyber safeguards on frontier weights; the reason the model exists

Agentic coding

Excellent

60.9% Terminal-Bench 4.0, the highest published score in the 5.1 release

General knowledge work

Good

Same weights as Fable 5.1, but no published index scores and no reason to prefer it here

Preços

Entrada

$10 / 1M tokens

Saída

$50 / 1M tokens

Contexto

1M context, $0.25/1M cache; vetted access

Ver preços completos

Testes de desempenho

TestePontuaçãoFonte
Terminal-Bench 4.060.9% Fonte

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